Location of the Small Intestine
The small intestine is located in the central and lower abdomen, extending from the duodenojejunal flexure (ligament of Treitz) to the ileocecal valve, measuring approximately 275-850 cm in adults.
Anatomical Position and Landmarks
The small intestine occupies a specific anatomical territory within the abdominal cavity:
- Starting point: The duodenojejunal flexure (ligament of Treitz), which marks the transition from the duodenum to the jejunum 1
- Ending point: The ileocecal valve, where the small intestine connects to the large intestine 2
- Length: Normal adult small intestinal length varies from approximately 275 cm to 850 cm when measured at surgery or autopsy, with women typically having shorter intestines than men 1
Regional Distribution
The small intestine consists of three segments with distinct locations:
- Duodenum: The proximal portion, located in the upper abdomen near the stomach and pancreas 3
- Jejunum: The middle segment, typically positioned in the left upper and central abdomen, caudal to the stomach 2, 3
- Ileum: The distal segment, extending into the right lower abdomen and pelvis, terminating at the ileocecal valve 3
Spatial Relationships
The small intestine's position relative to other structures:
- Located caudal (below) the liver and stomach 2
- The jejunum predominantly occupies the left side of the abdomen 2
- The terminal ileum is positioned in the right lower quadrant, connecting to the cecum 3
- The small bowel loops are contained within the peritoneal cavity, surrounded by the colon 3
This anatomical positioning is clinically relevant for surgical planning, imaging interpretation, and understanding disease processes affecting the small intestine.